A METHODOLOGY FOR PARAMETER-ESTIMATION IN SEAWEED PRODUCTIVITY MODELING

This paper presents a combined approach for parameter estimation in mo dels of primary production. The focus is on gross primary production a nd nutrient assimilation by seaweeds. A database of productivity deter minations, biomass and mortality measurements and nutrient uptake rate s obtained over one year for Gelidium sesquipedale in the Atlantic Oce an off Portugal has been used. Annual productivity was estimated by ha rvesting methods, and empirical relationships using mortality/wave ene rgy and respiration rates have been derived to correct for losses and to convert the estimates to gross production. In situ determinations o f productivity have been combined with data on the light climate (radi ation periods, intensity, mean turbidity) to give daily and annual pro ductivity estimates. The theoretical nutrient uptake calculated using a 'Redfield ratio' approach and determinations of in situ N and P cons umption by the algae during incubation periods have also been compared . The results of the biomass difference and incubation approaches are discussed in order to assess the utility of coefficients determined in situ for parameter estimation in seaweed production models.